High or low temperature thermostat with overthrow relief



March 7, 1967 E F. REIINGRUBERY 3,308,258

HIGH OR LOW TEMPERATURE THERMOSTAT WITH OVERTHROW RELIEF Filed July 23, 1965 I N VEN TOR. FRANK PE/NGIPUBEE v United States Patent Filed July 23, 1965, Ser. No. 474,430 1 Claim. (Cl. 200-139) The invention herein disclosed relates to thermostats of the probe type, in which a rod of less expansive material is confined to and operates within a tube of more expansive material and the general purposes of the invention are to provide a thermostat of this character, of simple,

sturdy construction, suitable for operation under either high or low temperature conditions and which in either event will be protected against injury from overthrow occasioned by excessive temperature changes.

Special objects of the invention are to provide this thermostat in a low cost, easily assembled structure and which will have convenient and practical means for accurately adjusting it to the desired temperature control and which further will have means for maintaining such adjustment against vibration or other disturbing effects.

The drawing accompanying and forming part of this specification is illustrative of present practical embodiments of the invention, which structure may be modified and changed as regards 'the immediate illustration; all within the true intent and scope of the invention, as hereinafter defined and claimed.

FIG. 1 is a side elevation of one of these new thermostats, parts broken away and appearing in section.

FIG. 2 is a part sectional top plan view of the device.

FIG. 3 is a broken longitudinal sectional view on substantially the plane of line 33 of FIG. 2.

FIG. 4 is a broken sectional detail illustrating parts in a different position.

FIGS. 1 and 2 show the body of the device in the form of a light sheet metal quadrangular case having parallel side walls 7, 8, connected in spaced relation "by parallel end walls 9, 10.

The end wall is integrally connected with the side walls 7, 8, and the other end wall 9 carries top and bottom walls 11, 12, closing the other three sides of the case.

The end wall 9 and the top and bottom walls 11, 12 have an-gularly extended flanges 13 which reach in over the side walls and enable the case to be secured by simple pin fastenings or rivets 14 extended through the ends of these flanges and through the side walls, adjacent the end wall 10.

This simple sturdy construction forms a mounting for the switch parts and for the probe which actuates the same.

The probe is shown as a tube 15 of highly expansive material, such as aluminum or brass, fixed to the end wall 10 by nut fastenings 16 and containing a rod 17 of less expansive material, secured to the tube at its outer end at 18 and having its inner end, inside the case, rounded at 19 to engage the switch mechanism.

The switch 20 is of rectangular shape having an op erating button 21 at the top and provided with terminals 22, 23 for wiring 24, brought out through the bottom of the case.

The switch block is mounted in and carried by a rocker of U-shaped formation having parallel sides 25, 26, opposed to the side walls of the case and connected in spaced relation by an end portion 27 opposed to the end wall 10 of the case in position to 'be engaged by the inner end 19 of the thermostatic rod.

This rocker is pivotally supported on a cross pin 28 fixed in the side walls of the case.

To provide a smooth bearing for the rounded inner end 19, of the lower expansion rod 17, the end wall 27 ice of the rocker is shown as having a rounded depression or seat 29 in which the end of the rod engages.

The bearing 29 for the rod is located, as shown in FIG. 3, above the pivot center 28 of the rocker and a coiled spring 30 is connected with the lower end of the rocker, below the pivot center and with an anchorage pin 31 extended between the sides of the case, so as to tension the rocker into or toward engagement with the end of the rod.

A rigid, light weight lever 32 as of channel construction as shown is pivoted at 33 in the case above the rocker in position to engage at its free end the switch operating button 21.

This lever is of such light weight that it may rest upon the switch button without operating the same but of such rigid construction that when backed up by an abutment screw it will eifect the desired operation of the switch.

This condition is illustrated in FIG. 3 where the rod 17 is shown as having traveled to the right far enough to permit the spring 30 to rotate the rocker in a right handed direction pressing the operating button 21 against the lever, with the lever held by the abutment screw 34 hearing on top of the same.

FIG. 4 shows the relation of the parts when the rod 17 is retracted into the case so as to shift the rocker in a left handed direction, against tension of spring 30, which yields to this movement.

The mechanism is thus protected against extreme or overthrow movement in either direction.

With outward travel, the rod is free to leave the rocket and the spring then simply pulls the switch up into engagement with the adjustable abutment screw.

Inward movement of the rod simply turns the rocker against tension of the spring as in FIG. 4, permitting the lever 32 to follow, leaving engagement with the adjusting screw, so that no harm results under extreme temperature changes in either direction.

The adjusting screw 34 is shown as having a suitably marked control knob 35 and as carrying a cam 36 engageable with an upstanding post 37, limiting the temperature adjustment.

To facilitate accurate temperature control and to hold the control against vibration or other disturbance, there is provided in the illustration a strip of spring metal 38 looped about the stem of the screw and having its ends extended and caught in a slot 39 in the top of the post 37.

This strip clamped about the screw permits the screw to be turned with a smooth adjustment action and holds the screw in the adjusted position against vibration or other influences.

To facilitate mounting of the thermostat, there is provided in the illustration an angular bracket 40 held to the case by One of the nuts 16 and projecting sufiicientlyfor screws of other fastenin-gs to support the thermostat in desired position.

The construction disclosed provides escape from injury under action in both directions, adapting the invention to operation under high heat conditions as in the neighborhood of 600 F. or under extreme low, sub-Zero conditions.

What is claimed is:

A thermostat for high or low temperature conditions, protected against excessive temperature changes in both fields of use comprising a quadrangular case having parallel side walls connected by parallel end walls,

a rocker pivoted in said case having parallel sides opposed to said side walls and a connecting end opposed to one of the end walls of the case,

a switch confined between the sides of said rocker and having an upwardly projecting operating member,

a thermally actuated member mounted on said last 3 mentioned end Wall of the case in opposition to and in engagement with the end of said rocker at a point to one side of the pivotal center of said rocker,

a spring connected with the end of said rocker and tensioning the same into engagement with said thermally actuated member,

a lever pivoted between the sides of said case above the rocker and in operating engagement with said actuating member of the switch,

an adjustment screw mounted on the case above said lever and engageable by said'lever as an abutment to limit upward movement of the lever, whereby to effect actuation of the switch on pivotal movement of the rocker effected by said spring under control of said thermally actuated member,

said thermally actuated member being freely separable from said rocker in one direction of movement whereby to permit said rocker to' remain in position determined by said adjusting screw operating as an abutment and said spring permitting unrestricted movement of the rocker in the opposite direction, said adjustment screw carrying a projecting stop member,

an upstanding post on the case engageable by said stop member, to limit the range of adjustment of said screw,

said post having a slot in the top of the same, and

a band of spring material looped about the stem of said screw and the ends of the same being engaged in said slot and holding said band stationary in frictional clamping engagement withthe screw and thereby yieldingly retaining said screw in various positions of adjustment.

References Cited by the Examiner UNITED STATES PATENTS 5/1947 Burling 200137 2,498,988 2/1950 Eden et a1 200137 3,098,140 7/1963 Reingruber 200137 A. LEWITTER, Assistant Examiner, 

